RELEASE: 00-125
DEEP SPACE 1 SPACECRAFT KEEPS GOING . . . AND GOING . . .
It has the little engine that could, and the pint-
sized power plant on board NASA's Deep Space 1 probe has
been doing it longer and more efficiently than anything
ever launched. The spacecraft, designed to test new
technologies, has run its unique propulsion system for more
than 200 days (4800 hours).
"The ion propulsion engine on Deep Space 1 has now
accumulated more operating time in space than any other
propulsion system in the history of the space program,"
said John Brophy, manager of the NASA Solar Electric
Propulsion Technology Applications Readiness project, at
the agency's Jet Propulsion Laboratory (JPL) in Pasadena,
CA.
Unlike the fireworks of most chemical rockets using solid
or liquid fuels, the ion drive emits only an eerie blue
glow as ionized (electrically charged) atoms of xenon are
pushed out of the engine. Xenon is the same gas found in
photo flash tubes and many lighthouse bulbs.
The almost imperceptible thrust from the system is
equivalent to the pressure exerted by a sheet of paper held
in the palm of your hand. The ion engine is very slow to
pick up speed, but over the long haul it can deliver 10
times as much thrust per pound of fuel as more traditional
rockets.
Previous ion propulsion systems, like those found on some
communications satellites, were not used as the main
engines, but only to keep the satellites on track. Deep
Space 1 is the first spacecraft to use this important
technology as its primary means of propulsion. The NASA
Space Electric Rocket Test 2, launched into Earth orbit in
1970, had the previous record for ion propulsion, thrusting
for about 161 days.
"The importance of ion propulsion is its great efficiency,"
says Dr. Marc Rayman, project manager for Deep Space 1. "It
uses very little propellant, and that means it weighs less
so it can use a less expensive launch vehicle and
ultimately go much faster than other spacecraft."
The ion particles travel out at about 68,000 miles per
hour. However, Deep Space 1 doesn't move that fast in the
other direction, because it's much heavier than the ion
particles. By the end of the mission, the ion engine will
have changed the spacecraft's speed by about 6,800 mph
(over 11,000 kph).
"This opens the solar system to many future exciting
missions which otherwise would have been unaffordable or
even impossible," added Dr. Rayman.
The technology is so efficient that it only consumes about
3.5 ounces (100 g) of xenon per day, taking about four days
to expend just one pound (0.4 kg).
The only other system that has operated longer is a ground-
based replica of the spacecraft's engine. The ongoing
extended-life test, being done in a vacuum test chamber at
JPL, has run its ion propulsion system for almost 500 days
(12,000 hours) and is scheduled to complete nearly 625 days
(15,000 hours) by the end of the year.
The Deep Space 1 ion engine could have a total operating
time of more than 583 days (14,000 hours) by the end of its
mission in the fall of 2001.
With its primary mission to serve as a technology
demonstrator - testing ion propulsion and 11 other
advanced technologies - successfully completed in
September 1999, Deep Space 1 is now headed for a rendezvous
with Comet Borrelly. NASA extended the mission, taking
advantage of the ion propulsion and other systems to target
a risky, but exciting, encounter with the comet in
September 2001.
But early in this bonus mission Deep Space 1 suffered a
serious setback with the loss of its star tracker
navigation system. Rather than abandon the project, NASA
engineers managed a deep-space rescue. They sent new
software, on-the-fly, turning an onboard camera into a
navigation instrument - all while Deep Space 1 was 200
million miles from Earth.
Deep Space 1 was launched in October 1998 as part of
NASA's New Millennium Program, which is managed by JPL for
NASA's Office of Space Science, Washington, DC. The
California Institute of Technology in Pasadena manages JPL
for NASA.
-end-
EDITOR'S NOTE: More information can be found on the Deep
Space 1 Home Page at:
http://nmp.jpl.nasa.gov/ds1/